There is a long and healthy tradition of "sister cities," where municipal leaders from different countries build ongoing relationships and exchange ideas.

The same spirit drives this Smarter Cities series, the second installment of our Worldcrunch Impact solutions journalism initiative. For experts in the field, a "smart city" may refer to those using the latest technology to improve urban planning and infrastructure, though we take a somewhat broader interpretation of the term to include policy and ideas that deserve attention for their...intelligence. 

Here is a rapid tour of 11 smart cities around the world and how they make a difference in the lives of their residents.